WO2018179707A1

WO2018179707A1 - Carboxylic acid group-containing polyester adhesive composition

Info

Publication number: WO2018179707A1
Application number: PCT/JP2018/001765
Authority: WO
Inventors: 遼薗田; 伊藤　武
Original assignee: 東洋紡株式会社
Priority date: 2017-03-28
Filing date: 2018-01-22
Publication date: 2018-10-04
Also published as: TWI746812B; KR20190126771A; TW201840794A; CN110268030A; CN110268030B; KR102433526B1; JPWO2018179707A1; JP7156267B2

Abstract

The purpose of the present invention is to provide a carboxylic acid group-containing polyester adhesive composition having an excellent sheet life and having sufficiently high wet heat resistance to withstand lead-free soldering under high humidity conditions while retaining good adhesion to various plastic films, metals (e.g., copper, aluminum, stainless steel) and glass epoxies. This adhesive composition comprises a carboxylic acid group-containing polyester resin (A) and a compound (B) having two or more glycidyl groups in each molecule, and is characterized in that the carboxylic acid group-containing polyester resin (A) has a glass transition temperature (Tg) of 40-90ºC and an acid value of 1-30 mgKOH, and contains, as copolymerization components, a polymer polyol (A1), a polymer polyol (A2) that is different from the polymer polyol (A1), and a tetracarboxylic dianhydride.

Description

Carboxylic acid group-containing polyester adhesive composition

The present invention relates to an adhesive composition excellent in adhesion to various plastic films, metals such as copper, aluminum, and stainless steel, glass epoxy, solder resistance, and sheet life, an adhesive sheet, and a printed wiring board including the same as a component. It is about.

In recent years, adhesives have been used in various fields, but due to diversification of purposes of use, various plastic films, adhesiveness to metal, glass epoxy, etc., moisture and heat resistance, etc., compared to conventionally used adhesives, There is a need for higher performance. For example, adhesives for circuit boards including flexible printed wiring boards (hereinafter sometimes abbreviated as FPC) are required to have adhesiveness, workability, electrical characteristics, and storage stability. Conventionally, epoxy / acryl butadiene adhesives, epoxy / polyvinyl butyral adhesives, and the like are used for this application.

In particular, in recent years, adhesives having higher heat resistance have been demanded from the viewpoint of compatibility with lead-free solder and the usage environment of FPC. In addition, solder resistance under high humidity is strongly demanded from the high density of wiring, the multi-layered FPC wiring board, and workability. In response to these problems, a resin composition for an adhesive mainly comprising a specific polyester or polyester / polyurethane and an epoxy resin is disclosed. However, these compositions may have poor pot life after blending and sheet life after coating / drying and may be difficult to distribute at room temperature (for example, Patent Documents 1 and 2).

JP 2010-84005 A JP 2009-096939 A

The problem of the present invention is to improve each of the problems of these conventional adhesives, and to maintain good adhesion to various plastic films, metals such as copper, aluminum and stainless steel, and glass epoxy. On the other hand, an object of the present invention is to provide a carboxylic acid group-containing polyester-based adhesive composition that is excellent in high heat and humidity resistance (solder resistance) and can be used for lead-free solder under high humidity and has excellent sheet life.

As a result of intensive studies, the present inventors have found that the above problems can be solved by the following means, and have reached the present invention. That is, the present invention has the following configuration.

An adhesive composition comprising a carboxylic acid group-containing polyester resin (A) and a compound (B) having two or more glycidyl groups in the molecule, wherein the carboxylic acid group-containing polyester resin (A) has a glass transition temperature ( Tg) is 40 to 90 ° C., acid value is 1 to 30 mg KOH / g, and the polymer polyol (A1) is different from the polymer polyol (A1) and the tetracarboxylic An adhesive composition comprising an acid dianhydride.

The polymer polyol (A1) and / or polymer polyol (A2) is preferably a polyester polyol.

An adhesive sheet containing a cured product of the adhesive composition. A printed wiring board comprising the adhesive sheet as a constituent element.

The carboxylic acid group-containing polyester-based adhesive composition of the present invention is a lead-free material under high humidity while maintaining good adhesion to various plastic films, metals such as copper, aluminum, and stainless steel, and glass epoxy. Excellent moisture and heat resistance (solder resistance) that can be applied to solder and excellent seat life.

<Polymer polyol (A1)>
The glass transition temperature of the polymer polyol (A1) is not particularly limited, but is preferably 0 ° C. or higher, more preferably 5 ° C. or higher. If the glass transition temperature is too low, the tackiness of the adhesive composition becomes strong, and bubbles are likely to be caught and poorly bonded. Moreover, it is preferable that it is 90 degrees C or less, More preferably, it is 80 degrees C or less, More preferably, it is 75 degrees C. If the glass transition temperature is too high, the coating film becomes brittle, and there is a concern that embrittlement becomes a problem or adhesion to the substrate is insufficient.

The acid value (mgKOH / g) of the polymer polyol (A1) is not particularly limited, but is preferably 0.1 or more, more preferably 0.3 or more, and further preferably 1 or more. If it is too small, crosslinking may be insufficient and the heat and humidity resistance may be reduced. Moreover, it is preferable that it is 10 or less, More preferably, it is 8 or less, More preferably, it is 6 or less. If it is too large, acid addition chain extension by tetracarboxylic dianhydride may not be possible. Therefore, since the crosslinking density becomes high and the coating film obtained from the adhesive composition becomes hard, there is a tendency that the adhesion is reduced.

The number average molecular weight (Mn1) of the polymer polyol (A1) is not particularly limited, but is preferably 10,000 or more, more preferably 11,000 or more, and further preferably 12,000 or more. When Mn1 is less than 10,000, the crosslink density increases and the coating film obtained from the adhesive composition becomes hard, so that the adhesive force tends to decrease. In addition, since it becomes difficult to relieve the water vapor stress generated during humidification soldering, the resistance to humidification soldering tends to deteriorate. Further, Mn1 is preferably 50,000 or less, more preferably 40,000 or less, and further preferably 30,000 or less. If it is too large, crosslinking may be insufficient and heat resistance may be reduced. The number average molecular weight (Mn1) of the polymer polyol (A1) is preferably larger than the number average molecular weight (Mn2) of the polymer polyol (A2) and the molecular weight of tetracarboxylic dianhydride. More preferably, it is maximum.

<Polymer polyol (A2)>
The polymer polyol (A2) is a polyol different from the polymer polyol (A1). The difference from the polymer polyol (A1) means that at least either the composition or the physical properties are different. The number average molecular weight (Mn2) of the polymer polyol (A2) is preferably 1,000 or more, more preferably 1,500 or more. If it is less than 1,000, the polymer polyol (A2) is likely to be bonded to each other, so that it tends to have a low molecular weight and a high acid value, the coating film becomes brittle, and there is a concern that embrittlement becomes a problem. Moreover, less than 10,000 is preferable, More preferably, it is 8,000 or less, More preferably, it is 7,000 or less, Most preferably, it is 5,000 or less. If it is 10,000 or more, acid addition chain extension by tetracarboxylic dianhydride may not be possible.

The difference between the number average molecular weight (Mn1) of the polymer polyol (A1) and the number average molecular weight (Mn2) of the polymer polyol (A2) is not particularly limited, but is preferably 2,000 or more, more preferably It is 3,000 or more, more preferably 4,000 or more. By providing the difference in molecular weight, it is possible to achieve an improvement in compatibility and solder resistance of the carboxylic acid group-containing polyester resin (A). That is, by increasing the molecular weight of one of the polymer polyols (A1) or (A2) as a long chain block, it is possible to relieve the stress generated during solder resistance evaluation. Moreover, since the amount of a carboxylic acid group can be adjusted by making the other into a short chain block, it becomes possible to provide solder resistance. Thereby, the improvement of solder resistance can be achieved. The upper limit of the difference in molecular weight is not particularly limited, but is preferably 40,000 or less, more preferably 30,000 or less, and still more preferably 20,000 or less.

The acid value (mgKOH / g) of the polymer polyol (A2) is not particularly limited, but is preferably 0.1 or more, more preferably 0.3 or more, and further preferably 1 or more. If it is too small, solder resistance may be inferior. Moreover, it is preferable that it is 10 or less, More preferably, it is 8 or less, More preferably, it is 6 or less. If it is too high, it may become impossible to extend the acid addition chain with tetracarboxylic dianhydride.

The glass transition temperature of the polymer polyol (A2) is not particularly limited, but is preferably −20 ° C. or higher, more preferably −10 ° C. or higher, still more preferably 0 ° C. or higher, and even more preferably 10 ° C. It is above, Especially preferably, it is 20 degreeC or more, Most preferably, it is 30 degreeC or more. If the glass transition temperature is too low, the tackiness of the adhesive composition tends to be strong, and bubbles are likely to bite and become defective during bonding. Moreover, it is preferable that it is 80 degrees C or less, More preferably, it is 70 degrees C or less. If the glass transition temperature is too high, the coating film becomes brittle and there is a concern that embrittlement becomes a problem.

The polymer polyol (A1) and / or polymer polyol (A2) is not particularly limited, but is preferably a polyester polyol.

<Polyester polyol>
The polyester polyol is preferably composed of a polycarboxylic acid component and a polyol component. As the polycarboxylic acid component constituting the polyester polyol, when the total polycarboxylic acid is 100 mol%, the aromatic dicarboxylic acid is preferably contained in an amount of 60 mol% or more. More preferably, it is 70 mol% or more, More preferably, it is 80 mol% or more, and it may be 100 mol%. If the amount is too small, the cohesive force of the coating film is weak, and the adhesive strength to various substrates may be reduced.

The aromatic dicarboxylic acid is not particularly limited, and examples thereof include terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid, and diphenic acid. Aromatic dicarboxylic acids having a sulfonic acid group such as sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, 5 (4-sulfophenoxy) isophthalic acid, And aromatic dicarboxylic acids having a sulfonate group such as metal salts and ammonium salts thereof. These can be used alone or in combination of two or more. Among these, terephthalic acid, isophthalic acid, and a mixture thereof are particularly preferable from the viewpoint of increasing the cohesive strength of the coating film.

Other polycarboxylic acid components include 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid and its anhydride, alicyclic dicarboxylic acids, succinic acid, adipic acid And aliphatic dicarboxylic acids such as azelaic acid, sebacic acid, dodecanedioic acid and dimer acid. In addition, 5-hydroxyisophthalic acid, p-hydroxybenzoic acid, p-hydroxyphenethyl alcohol, p-hydroxyphenylpropionic acid, p-hydroxyphenylacetic acid, 6-hydroxy-2-naphthoic acid, 4,4-bis (p An oxycarboxylic acid compound having a hydroxyl group and a carboxyl group in the molecular structure such as -hydroxyphenyl) valeric acid can also be used.

As the polyol component constituting the polyester polyol, when the total polyol is 100 mol%, the glycol component is preferably 90 mol% or more, more preferably 95 mol% or more, and 100 mol%. There is no problem.

The glycol component is preferably an aliphatic glycol, an alicyclic glycol, an aromatic-containing glycol, or an ether bond-containing glycol. Examples of aliphatic glycols include ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, 1,5- Pentanediol, 2,2-dimethyl-1,3-propanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, 2-ethyl-2-butylpropanediol (DMH), hydroxypivalic acid neopentyl glycol ester, dimethylol heptane, 2,2,4-trimethyl-1,3-pentanediol and the like. Examples of alicyclic glycols include 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, tricyclodecanediol, tricyclodecane dimethylol, spiroglycol, hydrogenated bisphenol A, and hydrogenated bisphenol A. Examples thereof include an ethylene oxide adduct and a propylene oxide adduct. Examples of ether bond-containing glycols include diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, neopentyl glycol ethylene oxide adduct, and neopentyl glycol propylene oxide adduct. Can be mentioned. Examples of aromatic-containing glycols include para-xylene glycol, meta-xylene glycol, ortho-xylene glycol, 1,4-phenylene glycol, ethylene oxide adducts of 1,4-phenylene glycol, bisphenol A, ethylene oxide addition of bisphenol A Examples thereof include glycols obtained by adding 1 to several moles of ethylene oxide or propylene oxide to two phenolic hydroxyl groups of bisphenols, such as products and propylene oxide adducts. These can be used alone or in combination of two or more. Of these, aliphatic glycols are preferable, and ethylene glycol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, or 1,6-hexanediol is more preferred.

In the polyester polyol, a tri- or higher functional component may be copolymerized with the polycarboxylic acid component and / or the polyol component for the purpose of introducing a branched skeleton if necessary. In the case of copolymerization, the total polycarboxylic acid component and the total polyol component are each 100 mol%, preferably 0.1 mol% or more, more preferably 0.5 mol% or more, and preferably 5 mol% or less. The mol% or less is more preferable. By making it within the above-mentioned range, particularly when a cured coating film is produced by reacting with a curing agent, a branched skeleton can be introduced, the terminal group concentration (reaction point) of the resin is increased, the crosslinking density is high, and the strength Can be obtained. On the other hand, if it exceeds 5 mol%, mechanical properties such as elongation at break of the coating film may be lowered, and gelation may occur during polymerization.

Examples of tri- or higher functional polycarboxylic acid components include trimellitic acid, trimesic acid, ethylene glycol bis (anhydro trimellitate), glycerol tris (anhydro trimellitate), trimellitic anhydride, pyromellitic anhydride (PMDA), oxydiphthalic dianhydride (ODPA), 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride (BTDA), 3,3 ′, 4,4′-diphenyltetracarboxylic dianhydride Product (BPDA), 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride (DSDA), 4,4 ′-(hexafluoroisopropylidene) diphthalic dianhydride (6FDA), 2,2 Examples thereof include compounds such as' -bis [(dicarboxyphenoxy) phenyl] propane dianhydride (BSAA). On the other hand, examples of the tri- or higher functional polyol include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol.

An acid value may be introduced into the polyester polyol. The acid value of the polyester polyol is preferably 10 mgKOH / g or less, and more preferably 8 mgKOH / g or less. If it is too high, it may become impossible to extend the acid addition chain with tetracarboxylic dianhydride. Moreover, 0.1 mgKOH / g or more is preferable and 0.3 mgKOH / g or more is more preferable. If it is too low, crosslinking may be insufficient and the heat and humidity resistance may be reduced.

Examples of the method for introducing an acid value include a method of introducing a carboxylic acid into a polyester polyol by acid addition after polymerization. If a monocarboxylic acid, dicarboxylic acid, or trifunctional or higher polycarboxylic acid compound is used for acid addition, the molecular weight may be reduced by transesterification. Therefore, a compound having at least one carboxylic anhydride group should be used. preferable. Carboxylic anhydrides include succinic anhydride, maleic anhydride, orthophthalic acid, 2,5-norbornene dicarboxylic acid anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride (PMDA), oxydiphthalic dianhydride Product (ODPA), 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride (BTDA), 3,3 ′, 4,4′-diphenyltetracarboxylic dianhydride (BPDA), 3,3 ', 4,4'-Diphenylsulfonetetracarboxylic dianhydride (DSDA), 4,4'-(hexafluoroisopropylidene) diphthalic dianhydride (6FDA), 2,2'-bis [(dicarboxyphenoxy ) Phenyl] propane dianhydride (BSAA) and the like.

<Tetracarboxylic dianhydride>
Examples of the tetracarboxylic dianhydride include an aromatic tetracarboxylic dianhydride, an aliphatic tetracarboxylic dianhydride, and an alicyclic tetracarboxylic dianhydride, and an aromatic tetracarboxylic dianhydride is preferable. Specifically, for example, pyromellitic anhydride (PMDA), oxydiphthalic dianhydride (ODPA), 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride (BTDA), 3,3 ′, 4,4′-diphenyltetracarboxylic dianhydride (BPDA), 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride (DSDA), 4,4 ′-(hexafluoroisopropylidene) diphthalate Examples thereof include acid dianhydride (6FDA) and 2,2′-bis [(dicarboxyphenoxy) phenyl] propane dianhydride (BSAA), and these can be used alone or in combination of two or more. Of these, pyromellitic anhydride is preferable.

<Carboxylic acid group-containing polyester resin (A)>
The glass transition temperature of the carboxylic acid group-containing polyester resin (A) of the present invention needs to be 40 ° C. or higher. Preferably it is 45 degreeC or more, More preferably, it is 50 degreeC or more. When the glass transition temperature is too low, the tackiness of the adhesive composition becomes strong, and bubbles are likely to bite at the time of bonding, resulting in insufficient sheet life. Moreover, it is necessary that it is 90 degrees C or less. Preferably it is 85 degrees C or less, More preferably, it is 80 degrees C or less. If the glass transition temperature is too high, the coating film becomes brittle and there is a concern that embrittlement becomes a problem.

The acid value of the carboxylic acid group-containing polyester resin (A) of the present invention is required to be 1 mgKOH / g or more. Preferably it is 5 mgKOH / g or more, More preferably, it is 10 mgKOH / g or more. Moreover, it is required that it is 30 mgKOH / g or less. Preferably it is 28 mgKOH / g or less, More preferably, it is 25 mgKOH / g or less. If the acid value is too small, sufficient solder resistance may not be obtained due to insufficient crosslinking, and if the acid value is too high, the crosslinking density becomes too high, the cured coating film becomes hard, and adhesiveness may decrease. . Moreover, the storage stability of the varnish which melt | dissolved the carboxylic acid group containing polyester resin (A) in the solvent falls, a crosslinking reaction advances easily at normal temperature, and the stable sheet life may not be obtained.

The carboxylic acid group-containing polyester resin (A) is a resin containing the polymer polyol (A1), the polymer polyol (A2), and tetracarboxylic dianhydride as a copolymerization component. The number average molecular weight (Mn3) of the carboxylic acid group-containing polyester resin (A) is preferably 1.7 times or less than the number average molecular weight (Mn1) of the polymer polyol (A1). That is, Mn3 / Mn1 ≦ 1.7. More preferably, it is 1.6 times or less. When it exceeds 1.7 times, it is considered that the difference in molecular weight is small or the amount of tetracarboxylic dianhydride is excessive. Therefore, the carboxylic acid group content of the carboxylic acid group-containing polyester resin (A) is insufficient, solder resistance is lowered, and the elastic modulus of the cured coating film is too high, so that the adhesiveness tends to be lowered. The lower limit of Mn3 / Mn1 is preferably 0.8 times or more, more preferably 0.9 times or more, and further preferably 1.0 times or more. If it is too small, there is a possibility that the reaction of only the polymer polyol (A2) and the chain extender (tetracarboxylic dianhydride) has occurred. Therefore, the block of the polymer polyol (A1) is sufficiently carboxylic dianhydride. There is a possibility that it will not react with the product and solder resistance will be insufficient. The carboxylic acid group-containing polyester resin (A) may be a resin containing only the polymer polyol (A1) and carboxylic dianhydride, or a polymer polyol (with a number average molecular weight (Mn3 / Mn1)). A resin containing only A2) and a carboxylic dianhydride may be included.

In the carboxylic acid group-containing polyester resin (A), the copolymer ratio of the polymer polyol (A1) and the polymer polyol (A2) is 100 parts by mass of the polymer polyol (A1). The amount is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and still more preferably 20 parts by mass or more. Further, it is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less. If the amount is too large, the moisture resistance solder resistance may be insufficient. The terminal which can react with a thing decreases, and heat resistance may become insufficient.

In the carboxylic acid group-containing polyester resin (A), the copolymerization ratio of the polymer polyol (A1) and the tetracarboxylic dianhydride is 0% by weight with respect to 100 parts by mass of the polymer polyol (A1). It is preferably 5 parts by mass or more, more preferably 1 part by mass or more, and still more preferably 2 parts by mass or more. Moreover, 10 mass parts or less are preferable, More preferably, it is 8 mass parts or less, More preferably, it is 5 mass parts or less. When too small, bridge | crosslinking may be insufficient and heat resistance may become insufficient, and when too large, it is a coating film. May become hard and sufficient adhesion may not be obtained.

The copolymerization amount of the polymer polyol (A1) in the carboxylic acid group-containing polyester resin (A) is preferably 30% by mass or more, more preferably 40% by mass or more, and further preferably 50% by mass or more. is there. By increasing the copolymerization amount of the polymer polyol (A1), it is possible to expect improvement in humidification solder resistance. Moreover, it is preferable that it is 90 weight% or less, More preferably, it is 85 mass% or less, More preferably, it is 80 mass% or less. If the amount is too large, the copolymerization amount of the polymer polyol (A2) or tetracarboxylic dianhydride may decrease, and solder resistance and adhesiveness may decrease.
The method for producing the carboxylic acid group-containing polyester resin (A) is not particularly limited, but is preferably solution polymerization or melt polymerization, more preferably solution polymerization.

<Epoxy resin (B)>
The epoxy resin (B) is not particularly limited as long as it cures and crosslinks with the carboxyl group of the carboxylic acid group-containing polyester resin (A), but is a polyfunctional epoxy resin having a plurality of epoxy groups in one molecule. Preferably there is. By using a polyfunctional epoxy resin, a cured coating film obtained from the adhesive composition can easily form a three-dimensional cross-link and improve heat resistance. Examples of the polyfunctional epoxy resin include a cresol novolac type epoxy resin, an epoxy resin having a dicyclopentadiene skeleton, and a phenol novolac type epoxy resin. When it is a cresol novolac type epoxy resin or a phenol novolac type epoxy resin, the crosslink density of the cured coating film can be lowered to relieve the stress at the time of peeling, thereby improving the solder resistance. Examples of commercially available cresol novolac epoxy resins include YDCN-700 manufactured by DIC Corporation. On the other hand, an epoxy resin having a dicyclopentadiene skeleton has a rigid dicyclopentadiene skeleton, so the hygroscopic property of the cured coating becomes extremely small, the crosslinking density of the cured coating is lowered, and the stress at the time of peeling is reduced. Can be relaxed. Therefore, solder resistance is improved. As a commercially available product of an epoxy resin having a dicyclopentadiene skeleton, HP7200 series manufactured by DIC can be mentioned. These can be used alone or in combination of two or more.

Furthermore, in addition to the polyfunctional epoxy resin, an epoxy resin containing a nitrogen atom can also be used. When an epoxy resin containing a nitrogen atom is used in combination, the coating film of the adhesive composition can be brought into a semi-cured state (hereinafter sometimes referred to as B stage) by heating at a relatively low temperature, and the B stage. There is a tendency that the workability in the bonding operation can be improved by suppressing the fluidity of the film. Moreover, since the effect which suppresses foaming of a B stage film can be anticipated, it is preferable. Examples of the epoxy resin containing a nitrogen atom include glycidylamines such as tetraglycidyldiaminodiphenylmethane, triglycidylparaaminophenol, tetraglycidylbisaminomethylcyclohexanone, N, N, N ′, N′-tetraglycidyl-m-xylenediamine and the like. The system etc. are mentioned. It is preferable that the compounding quantity of the epoxy resin containing these nitrogen atoms is 20 mass% or less of the whole epoxy resin (B). When the blending amount is more than 20% by mass, the rigidity becomes excessively high and the adhesiveness tends to be lowered, and the crosslinking reaction tends to proceed during storage of the adhesive sheet, and the sheet life tends to be lowered. The upper limit of the more preferable amount is 10 mass%, More preferably, it is 5 mass%.

Other epoxy resins can be used in combination as the epoxy resin (B) used in the present invention. For example, glycidyl ether type such as bisphenol A diglycidyl ether, bisphenol S diglycidyl ether, brominated bisphenol A diglycidyl ether, glycidyl ester type such as hexahydrophthalic acid glycidyl ester, dimer acid glycidyl ester, triglycidyl isocyanurate, 3 , 4-epoxycyclohexylmethyl carboxylate, epoxidized polybutadiene, alicyclic or aliphatic epoxide such as epoxidized soybean oil, and the like may be used alone or in combination of two or more.

The epoxy resin (B) is preferably 2 parts by mass or more, more preferably 5 parts by mass or more with respect to 100 parts by mass of the carboxylic acid group-containing polyester resin (A). Moreover, it is preferable that it is 50 mass parts or less, More preferably, it is 40 mass parts or less, More preferably, it is 30 mass parts or less. If the amount is too small, curing may be insufficient, and adhesiveness and heat-and-moisture resistance may decrease. If the amount is too large, uncrosslinked epoxy resin increases and solder resistance decreases. Moreover, the water absorption increases due to the hydroxyl group generated when the carboxylic acid and the epoxy group react with each other, and the heat and moisture resistance may deteriorate.

In the present invention, a curing catalyst can be used for the curing reaction of the epoxy resin (B). For example, imidazole compounds such as 2-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, or 1-cyanoethyl-2-ethyl-4-methylimidazole; Triethylamine, triethylenediamine, N′-methyl-N- (2-dimethylaminoethyl) piperazine, 1,8-diazabicyclo (5,4,0) -undecene-7, 1,5-diazabicyclo (4,3,0) -Tertiary amines such as nonene-5 or 6-dibutylamino-1,8-diazabicyclo (5,4,0) -undecene-7 and these tertiary amines in phenol, octylic acid or quaternized Compounds converted to amine salts with tetraphenylborate salts, etc .; triallylsulfonium hexafluoroan Cationic catalysts such as timonate or diallyl iodonium hexafluoroantimonate; and triphenylphosphine. Of these, 1,8-diazabicyclo (5,4,0) -undecene-7, 1,5-diazabicyclo (4,3,0) -nonene-5, or 6-dibutylamino-1,8-diazabicyclo (5 , 4,0) -undecene-7 and the like, and compounds obtained by converting these tertiary amines into amine salts with phenol, octylic acid, or quaternized tetraphenylborate salts are thermosetting and heat resistant. From the viewpoint of adhesion to metal and storage stability after blending. The blending amount of the curing catalyst is preferably 0.01 to 1.0 part by mass with respect to 100 parts by mass of the carboxylic acid group-containing polyester resin (A). If it is this range, the catalytic effect with respect to reaction of carboxylic acid group containing polyester resin (A) and an epoxy resin (B) will increase further, and firm adhesive performance can be acquired.

<Organic solvent>
The adhesive composition of the present invention can be dissolved in an organic solvent to form a resin solution. The organic solvent is not particularly limited as long as it dissolves the carboxylic acid group-containing polyester resin (A), and more preferably dissolves the epoxy resin (B). Examples of the organic solvent include aromatic hydrocarbons such as benzene, toluene, and xylene, cycloaliphatic hydrocarbons such as cyclohexane, cyclohexene, methylcyclohexane, and ethylcyclohexane, methanol, ethanol, isopropyl alcohol, butanol, pentanol, hexanol, Alcohol solvents such as propanediol and phenol, acetone solvents such as methyl isobutyl ketone, methyl ethyl ketone, pentanone, hexanone, cyclohexanone, isophorone, and acetophenone , Ester solvents such as butyl acetate, methyl propionate and butyl formate, and halogenated hydrocarbons such as trichloroethylene, dichloroethylene, chlorobenzene and chloroform Can be used, it can be used in combination of these one or more. Of these, a mixed solvent of an aromatic hydrocarbon and a ketone solvent is preferable, and a mixed solvent of toluene and methyl ethyl ketone is more preferable.

The amount of the organic solvent is preferably 50 parts by mass or more, more preferably 70 parts by mass or more, and further preferably 100 parts by mass or more with respect to 100 parts by mass of the carboxylic acid group-containing polyester resin (A). . Moreover, it is preferable that it is 700 mass parts or less, More preferably, it is 600 mass parts or less, More preferably, it is 500 mass parts or less. If the amount is too small, the storage stability of the adhesive composition may be lowered. If the amount is too large, it may be industrially disadvantageous.

<Other additives>
The adhesive composition of the present invention can further contain various curable resins and additives as long as the effects of the present invention are not impaired. Examples of the curable resin include phenolic resins, amino resins, isocyanate compounds, and silane coupling agents.

Examples of phenolic resins include formaldehyde condensates of alkylated phenols and cresols. Specifically, alkylated (eg, methyl, ethyl, propyl, isopropyl, butyl) phenol, p-tert-amylphenol, 4,4′-sec-butylidenephenol, p-tert-butylphenol, o-cresol, m -Cresol, p-cresol, p-cyclohexylphenol, 4,4'-isopropylidenephenol, p-nonylphenol, p-octylphenol, 3-pentadecylphenol, phenol, phenyl-o-cresol, p-phenylphenol, xylenol, etc. Formaldehyde condensates. These can be used alone or in combination of two or more.

Examples of amino resins include formaldehyde adducts such as urea, melamine, and benzoguanamine, and alkyl ether compounds of these alcohols having 1 to 6 carbon atoms. Specific examples include methoxylated methylol urea, methoxylated methylol N, N-ethyleneurea, methoxylated methylol dicyandiamide, methoxylated methylol melamine, methoxylated methylol benzoguanamine, butoxylated methylol melamine, butoxylated methylol benzoguanamine and the like. Preferred are methoxylated methylol melamine, butoxylated methylol melamine, and methylolated benzoguanamine, each of which can be used alone or in combination.

Examples of the isocyanate compound include aromatic or aliphatic diisocyanates and trivalent or higher polyisocyanates, which may be either low molecular compounds or high molecular compounds. Examples thereof include tetramethylene diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, and trimers of these isocyanate compounds. Further, an excess amount of these isocyanate compounds, for example, low molecular active hydrogen compounds such as ethylene glycol, propylene glycol, trimethylolpropane, glycerin, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, or triethanolamine, or various polyester polyols, Examples thereof include terminal isocyanate group-containing compounds obtained by reacting polyether polyols, polyamides and other polymer active hydrogen compounds.

The isocyanate compound may be a blocked isocyanate. Examples of the isocyanate blocking agent include phenols such as phenol, thiophenol, methylthiophenol, cresol, xylenol, resorcinol, nitrophenol, and chlorophenol; oximes such as acetoxime, methylethyl ketoxime, and cyclohexanone oxime; methanol, ethanol, propanol, Alcohols such as butanol; halogen-substituted alcohols such as ethylene chlorohydrin and 1,3-dichloro-2-propanol; tertiary alcohols such as t-butanol and t-pentanol; ε-caprolactam, δ-valero And lactams such as lactam, γ-butyrolactam, and β-propyllactam. Other examples include aromatic amines, imides, active methylene compounds such as acetylacetone, acetoacetate ester, and malonic acid ethyl ester, mercaptans, imines, ureas, diaryl compounds, and sodium bisulfite. The blocked isocyanate is obtained by subjecting the above isocyanate compound, isocyanate compound and isocyanate blocking agent to an addition reaction by a conventionally known appropriate method.

A silane coupling agent may be blended in the adhesive composition of the present invention as necessary. It is very preferable to add a silane coupling agent because adhesion to metal and heat resistance are improved. Although it does not specifically limit as a silane coupling agent, What has an unsaturated group, What has a glycidyl group, What has an amino group, etc. are mentioned. Examples of the silane coupling agent having an unsaturated group include vinyltris (β-methoxyethoxy) silane, vinyltriethoxysilane, and vinyltrimethoxysilane. Examples of silane coupling agents having a glycidyl group include γ-glycidoxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltriethoxysilane. Etc. Examples of the silane coupling agent having an amino group include N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, N-phenyl-γ. -Aminopropyltrimethoxysilane and the like. Of these, from the viewpoint of heat resistance, γ-glycidoxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltriethoxysilane, etc. A silane coupling agent having a glycidyl group is preferred. The compounding amount of the silane coupling agent is preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of the carboxylic acid group-containing polyester resin (A). When the blending amount of the silane coupling agent is less than 0.5 parts by mass, the resulting adhesive composition may have poor heat resistance, and when it exceeds 20 parts by mass, heat resistance or adhesion may be poor. There is.

In the adhesive composition of the present invention, flame retardants such as bromine-based, phosphorus-based, nitrogen-based, and metal hydroxide compounds, leveling agents, pigments, dyes, and other additives can be appropriately blended as necessary.

<Adhesive sheet>
In this invention, an adhesive sheet contains the coating film (henceforth an adhesive bond layer) of the adhesive composition obtained by hardening the adhesive composition of this invention. The adhesive sheet has a function of adhering a base material to an adherend by an adhesive layer. The base material of the adhesive sheet functions as a protective layer for the adherend after adhesion. When a release substrate is used, the release substrate can be released and the adhesive layer can be transferred to another adherend. The adhesive sheet is obtained by applying the adhesive composition to a substrate or a release substrate, drying, and curing. Specific configurations include a base material / adhesive layer, a release base material / adhesive layer, a release base material / adhesive layer / base material, a release base material / adhesive layer / release base material, etc. Is mentioned. Moreover, depending on the case, the adhesive agent layer which peeled the mold release base material independently may be sufficient. The adhesive sheet may contain a trace amount or a small amount of an organic solvent.

The adhesive sheet can be obtained by applying the adhesive composition of the present invention to various substrates according to a conventional method, removing at least a part of the solvent and drying. In addition, after removing at least a part of the solvent and drying, pasting the release substrate to the adhesive layer makes it possible to roll up without causing the substrate to be transferred to the substrate, and is excellent in operability and adhesion. Since the agent layer is protected, it is excellent in storage stability and easy to use. In addition, after applying and drying on the release substrate, if another release substrate is attached as necessary, the adhesive layer itself can be transferred to another substrate.

The substrate is not particularly limited, and examples thereof include a film-like resin, a metal plate, a metal foil, and papers. Examples of the film-like resin include polyester resin, polyamide resin, polyimide resin, polyamideimide resin, and olefin resin. Examples of metal plate and metal foil materials include various metals such as SUS, copper, aluminum, iron, and zinc, and alloys and plated products thereof. Glassine paper etc. can be illustrated. Moreover, glass epoxy etc. can be illustrated as a composite material. Polyester resin, polyamide resin, polyimide resin, polyamideimide resin, SUS steel plate, copper foil, aluminum foil, and glass epoxy are preferable from the viewpoint of adhesive strength between the substrate and the adhesive composition and durability.

The release substrate is not particularly limited. For example, a coating layer of a sealant such as clay, polyethylene, or polypropylene is provided on both surfaces of paper such as fine paper, kraft paper, roll paper, and glassine paper. Furthermore, those in which a silicone-type, fluorine-type, or alkyd-type release agent is applied on each of the coating layers. In addition, various olefin films such as polyethylene, polypropylene, ethylene-α-olefin copolymer, propylene-α-olefin copolymer, and those obtained by applying the release agent on a film such as polyethylene terephthalate can be used. For the reasons such as the release force between the release substrate and the adhesive layer, and the adverse effect of silicone on the electrical characteristics, polypropylene seal treatment is applied to both sides of the fine paper and an alkyd release agent is used on it. Or what uses an alkyd type mold release agent on polyethylene terephthalate is preferred.

The method for coating the adhesive composition on the substrate or the release substrate is not particularly limited, and examples thereof include a comma coater and a reverse roll coater. Alternatively, if necessary, an adhesive layer can be provided directly or by a transfer method on a rolled copper foil, which is a printed wiring board constituent material, or a polyimide film. The thickness of the adhesive layer after drying is appropriately changed as necessary, but is preferably in the range of 5 to 200 μm. If the thickness of the adhesive layer is less than 5 μm, the adhesive strength may be insufficient. If it exceeds 200 μm, the drying is insufficient, the residual solvent is increased, and there is a problem that blisters are generated at the time of printing printed circuit board production. The drying conditions are not particularly limited, but the residual solvent ratio after drying is preferably 4% by mass or less, and more preferably 1% by mass or less. If it exceeds 4% by mass, there may be a problem that the residual solvent is foamed when the printed wiring board is pressed to cause swelling.

<Printed wiring board>
The printed wiring board in the present invention includes an adhesive sheet as a constituent element, and more specifically, a laminate (metal foil / adhesive layer / resin base) formed of a metal foil and a resin base material forming a conductor circuit. Material) as a component. A printed wiring board is manufactured by conventionally well-known methods, such as a subtractive method, using a metal-clad laminated body, for example. If necessary, a so-called flexible circuit board (FPC), flat cable, tape automated bonding (covered by using a cover film or screen printing ink, etc., partially or entirely covered with a conductor circuit formed of metal foil (tape automated bonding) TAB) circuit board and the like.

The printed wiring board of the present invention can have any laminated structure that can be employed as a printed wiring board. For example, it can be set as the printed wiring board comprised from four layers, a base film layer, a metal foil layer, an adhesive bond layer, and a cover film layer. For example, it can be set as the printed wiring board comprised from five layers, a base film layer, an adhesive bond layer, a metal foil layer, an adhesive bond layer, and a cover film layer. The printed wiring board may be reinforced with a reinforcing material as necessary. In that case, the reinforcing material and the adhesive layer are provided under the base film layer.

Furthermore, if necessary, a configuration in which two or three or more of the above-described printed wiring boards are laminated may be employed.

The adhesive composition of the present invention can be suitably used for each adhesive layer of a printed wiring board. In particular, when the adhesive composition of the present invention is used as an adhesive, it has high adhesiveness to the base material constituting the printed wiring board and can impart high heat resistance that can also be used for lead-free solder. Is possible. In particular, in the high-temperature range where solder resistance is evaluated, the chemical cross-linking between the resin and the resin and the physical cross-linking between the resin and the inorganic filler are provided in a well-balanced manner. It is possible to relieve stress without swelling or deformation. Therefore, it is suitable for bonding between the metal foil layer and the cover film layer, and bonding between the base film layer and the reinforcing material layer. In particular, when a metal reinforcing material such as a SUS plate or an aluminum plate is used, moisture cannot evaporate from the reinforcing material side when soldering in a humidified state, so the adhesive layer between the base film layer and the reinforcing material layer is used. The impact exerted is particularly strong and is suitable as an adhesive composition used for adhesion in such a case.

The inorganic filler used in the present invention is not particularly limited. For example, alumina, silica, titania, tantalum oxide, zirconia, silicon nitride, barium titanate, barium carbonate, lead titanate, lead zirconate titanate, titanium Lead lanthanum zirconate, gallium oxide, spinel, mullite, cordierite, talc, aluminum hydroxide, magnesium hydroxide, aluminum titanate, yttria-containing zirconia, barium silicate, boron nitride, calcium carbonate, calcium sulfate, zinc oxide Zinc borate, magnesium titanate, magnesium borate, barium sulfate, organic bentonite, carbon, and the like can be used, and these may be used alone or in combination of two or more. Silica is preferable from the viewpoint of transparency, mechanical properties, and heat resistance of the adhesive composition, and fumed silica having a three-dimensional network structure is particularly preferable. In addition, hydrophobic silica treated with monomethyltrichlorosilane, dimethyldichlorosilane, hexamethyldisilazane, octylsilane, silicone oil or the like is more preferable for imparting hydrophobicity. When using fumed silica as the inorganic filler, the average diameter of the primary particles is preferably 30 nm or less, more preferably 25 nm or less. When the average diameter of the primary particles exceeds 30 nm, the interaction between the particles and the resin tends to decrease, and the heat resistance tends to decrease. In addition, the average diameter of a primary particle said here is an average value of the circle equivalent diameter of 100 particle | grains extracted randomly from the primary particle image obtained using the scanning electron microscope.

The compounding amount of the inorganic filler is preferably 10 parts by mass or more, more preferably 13 parts by mass or more, and further preferably 15 parts by mass or more with respect to 100 parts by mass of the carboxylic acid group-containing polyester resin (A). If it is less than 10 parts by mass, the effect of improving heat resistance may not be exhibited. Moreover, it is preferable that it is 50 mass parts or less, More preferably, it is 45 mass parts or less, More preferably, it is 40 mass parts or less. If it exceeds 50 parts by mass, the inorganic filler may be poorly dispersed, the solution viscosity may become too high, resulting in problems in workability, or the adhesiveness may be lowered.

In the printed wiring board of the present invention, any resin film conventionally used as a substrate for printed wiring boards can be used as the substrate film. As the resin for the base film, a resin containing halogen may be used, or a resin not containing halogen may be used. From the viewpoint of environmental problems, a resin containing no halogen is preferable. However, from the viewpoint of flame retardancy, a resin containing halogen can also be used. The base film is preferably a polyimide film or a polyamideimide film.

As the metal foil used in the present invention, any conventionally known conductive material that can be used for a circuit board can be used. As the material, for example, copper foil, aluminum foil, steel foil, nickel foil and the like can be used, and composite metal foil obtained by combining these and metal foil treated with other metals such as zinc and chromium compounds are also used. be able to. Preferably, it is a copper foil.

The thickness of the metal foil is not particularly limited, but is preferably 1 μm or more, more preferably 3 μm or more, and further preferably 10 μm or more. Moreover, it is preferably 50 μm or less, more preferably 30 μm or less, and still more preferably 20 μm or less. If the thickness is too thin, it may be difficult to obtain sufficient electrical performance of the circuit. On the other hand, if the thickness is too thick, the processing efficiency at the time of circuit fabrication may be reduced.

Metal foil is usually provided in the form of a roll. The form of the metal foil used when manufacturing the printed wiring board of this invention is not specifically limited. When a roll-shaped metal foil is used, its length is not particularly limited. The width is not particularly limited, but is preferably about 250 to 1000 mm.

As the cover film, any conventionally known insulating film can be used as an insulating film for a printed wiring board. For example, films produced from various polymers such as polyimide, polyester, polyphenylene sulfide, polyethersulfone, polyetheretherketone, aramid, polycarbonate, polyarylate, polyimide, and polyamideimide can be used. More preferably, it is a polyimide film or a polyamidoimide film, More preferably, it is a polyimide film.

As the material resin for the cover film, a resin containing halogen may be used, or a resin not containing halogen may be used. From the viewpoint of environmental problems, a resin containing no halogen is preferable. However, from the viewpoint of flame retardancy, a resin containing halogen can also be used.

The printed wiring board of the present invention can be manufactured using any conventionally known process except that the material of each layer described above is used.

In a preferred embodiment, a semi-finished product in which an adhesive layer is laminated on a cover film layer (hereinafter referred to as “cover film side semi-finished product”) is manufactured. On the other hand, an adhesive layer is laminated on a semi-finished product (hereinafter referred to as “base film side two-layer semi-product”) or a base film layer in which a desired circuit pattern is formed by laminating a metal foil layer on the base film layer. And a semi-finished product (hereinafter referred to as “base film side three-layer semi-product”) having a desired circuit pattern formed by laminating a metal foil layer thereon (hereinafter referred to as base film side two-layer semi-product) The base film side three-layer semi-finished product is collectively referred to as “base film side semi-finished product”). A four-layer or five-layer printed wiring board can be obtained by laminating the cover film side semi-finished product and the base film side semi-finished product thus obtained.

The base film side semi-finished product includes, for example, (A) a step of applying a solution of a resin to be a base film to the metal foil, and initial drying of the coating film, and (B) the metal foil obtained in (A) It can be obtained by a production method including a step of heat-treating and drying the laminate with the initial dry coating film (hereinafter referred to as “heat treatment / solvent removal step”).

A conventionally known method can be used to form a circuit in the metal foil layer. An active method may be used and a subtractive method may be used. The subtractive method is preferable.

The obtained base film side semi-finished product may be used as it is for pasting with the cover film side semi-finished product. May be used.

The cover film side semi-finished product is manufactured, for example, by applying an adhesive to the cover film. If necessary, a crosslinking reaction in the applied adhesive can be performed. In a preferred embodiment, the adhesive layer is semi-cured.

The obtained cover film-side semi-finished product may be used as it is for pasting with the base-side semi-finished product, or after being laminated and stored with the release film for pasting with the base-film-side semi-finished product. May be used.

The base film side semi-finished product and the cover film side semi-finished product are each stored, for example, in the form of a roll, and then bonded together to produce a printed wiring board. Arbitrary methods can be used as a method of bonding, for example, it can bond using a press or a roll. Further, the two can be bonded together while heating by a method such as using a heating press or a heating roll device.

The base film side semi-finished product, the cover film side semi-finished product, and the reinforcing agent side semi-finished product are all laminated bodies for printed wiring boards in the present invention.

Although the adhesive composition of the present invention is suitably used for each adhesive layer of a printed wiring board, it is excellent in adhesion to various base materials and moisture and heat resistance. By containing conductive powder, it can be used for electromagnetic shielding applications, touch panel and electronic component circuit forming applications, terminals and lead wire conductive adhesives, and the like.

In order to describe the present invention in more detail, examples and comparative examples are given below, but the present invention is not limited to the examples. In addition, each measured value described in the Example and the comparative example was measured by the following method. Unless otherwise specified, “part” means “part by mass” and “%” means “% by mass”.

Polymerization Example of Polymer Polyol (A1-1) In a reaction vessel equipped with a stirrer, thermometer and effluent cooler, 90 parts of terephthalic acid, 358 parts of isophthalic acid, 5 parts of trimellitic anhydride, 2-methyl- 319 parts of 1,3-propanediol, 172 parts of 1,4-cyclohexanediol and 0.2 part of tetrabutyl titanate were added, the temperature was gradually raised to 250 ° C., and the esterification reaction was carried out while removing distilled water from the system. Went. After completion of the esterification reaction, initial polymerization was carried out while gradually reducing the pressure to 10 mmHg, the temperature was raised to 250 ° C., and further, late polymerization was carried out until a predetermined torque was reached at 1 mmHg or less. Thereafter, the pressure was returned to normal pressure with nitrogen, 5 parts of trimellitic anhydride was added, and the mixture was reacted at 220 ° C. for 30 minutes to obtain a polymer polyol (A1). The composition and characteristic values of the polymer polyol (A1) thus obtained are shown in Table 1. Each measurement evaluation item followed the above-mentioned method.

Polymerization Example of Polymer Polyol (A2-1) In a reaction vessel equipped with a stirrer, a thermometer, and an outflow condenser, 390 parts of terephthalic acid, 390 parts of isophthalic acid, 367 parts of ethylene glycol, 2,2-dimethyl- First, 362 parts of 1,3-propanediol and 0.2 part of tetrabutyl titanate were added, the temperature was gradually raised to 250 ° C., and the esterification reaction was performed while removing distilled water out of the system. After the esterification reaction is completed, initial polymerization under reduced pressure is performed while gradually reducing the pressure to 10 mmHg, the temperature is increased to 250 ° C., and further polymerization is performed until a predetermined torque is reached at 1 mmHg or less, whereby a polymer polyol (A2-1) is obtained. ) Table 1 shows the composition and characteristic values of the polymer polyol (A2-1) thus obtained. Each measurement evaluation item followed the above-mentioned method.

Polymer polyols (A1-2 to A1-5) were obtained in the same manner as the polymer polyol (A1-1). Further, the polymer polyol (A2-2) was obtained in the same manner as the polymer polyol (A2-1). These characteristic values are shown in Table 1.

(1) Composition of carboxylic acid group-containing polyester resin (A) The carboxylic acid group-containing polyester resin (A) was dissolved in deuterated chloroform, and the molar ratio of each component was determined by ¹ H-NMR analysis.

(2) Number average molecular weight (Mn)
A sample (carboxylic acid group-containing polyester resin (A), polymer polyol (A1) or polymer polyol (A2)) was dissolved or diluted in tetrahydrofuran so that the sample concentration was about 0.5% by mass, and the pore size was 0. A sample for measurement was filtered through a membrane filter made of polytetrafluoroethylene of 5 μm. The number average molecular weight was measured by gel permeation chromatography using tetrahydrofuran as the mobile phase and a differential refractometer as the detector. The flow rate was 1 mL / min and the column temperature was 30 ° C. As the column, KF-802, 804L and 806L manufactured by Showa Denko were used. Monodisperse polystyrene was used as the molecular weight standard. However, when the sample did not dissolve in tetrahydrofuran, N, N-dimethylformamide was used instead of tetrahydrofuran. Low molecular compounds (oligomers and the like) having a number average molecular weight of less than 1000 were omitted without counting.

(3) Glass transition temperature With a differential scanning calorimeter “DSC220 type” manufactured by Seiko Denshi Kogyo Co., Ltd., 5 mg of a measurement sample is put in an aluminum pan, sealed with a lid, and once held at 250 ° C. for 5 minutes. The sample was quenched with liquid nitrogen and then measured from −150 ° C. to 250 ° C. at a temperature increase rate of 20 ° C./min. The inflection point of the obtained curve was taken as the glass transition temperature. When there were two or more inflection points, it was considered that block copolymerization was performed, and each mutation point was read and handled as having a plurality of glass transition temperatures.

(4) Acid value 0.2 g of a sample (carboxylic acid group-containing polyester resin (A), polymer polyol (A1) or polymer polyol (A2)) is dissolved in 20 ml of chloroform, and phenolphthalein is used as an indicator. Titrated with 0.1N potassium hydroxide ethanol solution. From this titration amount, the acid number (mgKOH / g) was calculated by converting the number of mg of KOH consumed for neutralization into the amount per 1 g of resin.

<Synthesis Example of Carboxylic Acid Group-Containing Polyester Resin (A-1)>
In a reaction can equipped with a stirrer, a thermometer, and a reflux tube, 160 parts of a polymer polyol (A1), 40 parts of a polymer polyol (A2), 5.2 parts of pyromellitic anhydride, and 200 parts of toluene were charged. The solution was dissolved in toluene while gradually raising the temperature to 0 ° C. After the dissolution was completed, 0.1 part of triethylamine was added as a reaction catalyst, and then the temperature was gradually raised to 105 ° C. and reacted for 24 hours. After confirming the completion of the reaction by IR, a solution with a solid content concentration of 40% of the carboxylic acid group-containing polyester resin (A-1) was obtained by diluting with 108 parts of toluene. The composition and characteristic values of the carboxylic acid group-containing polyester resin (A-1) thus obtained are shown in Table 2. Each measurement evaluation item followed the above-mentioned method.

<Synthesis examples of carboxylic acid group-containing polyester resins (A-2) to (A-10)>
Carboxylic acid group-containing polyester resins (A-2) to (A-10) were obtained in the same manner as in Synthesis example (A-1) of carboxylic acid group-containing polyester resin.

<Example 1>
To 100 parts of the solid content of the carboxylic acid group-containing polyester resin (A-1), as an epoxy resin, 9 parts of YDCN-700-10 (Novolac type epoxy resin) manufactured by Nippon Steel & Sumikin Chemical Co., Ltd. and Mitsubishi Gas Chemical Co., Ltd. Add 0.1 part of TETRAD (registered trademark) -X (N, N, N ′, N′-tetraglycidyl-m-xylenediamine) and adjust the solid content concentration to 35% using methyl ethyl ketone. An adhesive composition was obtained. The obtained adhesive composition was evaluated by the method shown below.

<Examples 2 to 13 and Comparative Examples 1 and 2>
Carboxylic acid group-containing polyester resin and epoxy resin were changed to those shown in Table 3, and changed to the respective compounding amounts shown in Table 3 in the same manner as in Example 1. Examples 2 to 13 and Comparative Examples Performed 1-2. The results are shown in Table 3.

(5) Peel strength, solder resistance, sheet life (5) -1 Peel strength (adhesiveness)
The adhesive composition obtained in Examples or Comparative Examples was applied to a polyimide film having a thickness of 12.5 μm (manufactured by Kaneka Corporation, Apical (registered trademark)) so that the thickness after drying was 25 μm. The film was dried at 5 ° C. for 5 minutes to obtain an adhesive film (B stage product). The adhesive film surface of the adhesive film was bonded so that the glossy surface of 20 μm rolled copper foil was in contact, and pressed at 160 ° C. under a pressure of 30 kgf / cm ² for 30 seconds to adhere. Subsequently, it was cured by heat treatment at 140 ° C. for 4 hours to prepare a sample for evaluation.

Peel strength: A sample for evaluation was drawn at 25 ° C., a film was drawn, a 180 ° peel test was conducted at a tensile speed of 50 mm / min, and the peel strength was measured. This test shows the peel strength at room temperature. In consideration of practical performance, it is preferably 3.5 N / cm or more, more preferably 5 N / cm or more.
Evaluation criteria ◎: 10 N / cm or more ○: 5 N / cm or more, less than 10 N / cm Δ: 3.5 N / cm or more, less than 5 N / cm ×: less than 3.5 N / cm

(5) -2 Solder Resistance Solder Resistance (Dry): After leaving the sample for evaluation in an environment of 120 ° C. for 30 minutes, the sample is floated in a heated solder bath for 1 minute, and the upper limit temperature at which swelling does not occur is 10 Measured at a pitch of ° C. In this test, a higher measured value indicates better heat resistance. In consideration of practical performance, 350 ° C. or higher is preferable, and 360 ° C. or higher is more preferable.
Evaluation criteria A: No swelling even at 360 ° C. or higher.
○: No swelling at 350 ° C. or more and less than 360 ° C.
Δ: No swelling at 340 ° C. or higher and lower than 350 ° C.
X: Swelled at less than 340 ° C.

Solder resistance (humidification): The sample for evaluation was allowed to stand at 40 ° C. and 80% humidification for 3 days, then floated in a heated solder bath for 1 minute, and the upper limit temperature at which swelling did not occur was measured at a pitch of 10 ° C. In this test, it shows that the higher the measured value has better heat resistance, but it is also necessary to suppress the impact due to evaporation of water vapor contained in each base material and adhesive layer, rather than the dry state, More severe heat resistance is required. In consideration of practical performance, 260 ° C. or higher is preferable, and 270 ° C. or higher is more preferable.
Evaluation criteria A: No swelling even at 270 ° C. or higher.
○: No swelling at 260 ° C. or higher and lower than 270 ° C.
Δ: No swelling at 250 ° C. or higher and lower than 260 ° C.
X: Swelled at less than 250 ° C.

(5) -3 Evaluation of sheet life Preparation of sheet life measurement sample: 12.5 μm-thick polyimide film (Apical (registered trademark) manufactured by Kaneka Corporation) with the adhesive composition obtained in the examples or comparative examples ) Was dried to a thickness of 25 μm and dried at 130 ° C. for 5 minutes to obtain an adhesive film (B stage product). This B-stage product was left in an environment of 40 ° C. × 80% for 2 weeks. The B stage product was bonded to the adhesive layer surface of the adhesive film so that the glossy surface of the 20 μm rolled copper foil was in contact, and pressed at 160 ° C. under a pressure of 30 kgf / cm ² for 30 seconds to be bonded. Subsequently, it was cured by heat treatment at 140 ° C. for 4 hours to prepare a sample for evaluation. Evaluation samples for peel strength and solder resistance were prepared in the same manner as described above.

According to the examples in Table 3, it can be seen that the adhesive composition of the present invention is excellent in initial peel strength, solder resistance, and sheet life.

The adhesive compositions in Comparative Examples 1 to 3 have insufficient performance in terms of peel strength, solder resistance, sheet life, and the like.

The adhesive composition of the present invention is excellent in adhesion to various plastic films, metals such as copper, aluminum, and stainless steel, glass epoxy, solder resistance, and sheet life. Therefore, it is particularly useful as an adhesive for circuit boards including FPC.

Claims

An adhesive composition comprising a carboxylic acid group-containing polyester resin (A) and an epoxy resin (B), wherein the carboxylic acid group-containing polyester resin (A) has a glass transition temperature (Tg) of 40 to 90 ° C., an acid value Is 1 to 30 mg KOH / g, and contains a polymer polyol (A1) as a copolymerization component, a polymer polyol (A2) different from the polymer polyol (A1), and a tetracarboxylic dianhydride, An adhesive composition.
The adhesive composition according to claim 1, wherein the polymer polyol (A1) and / or the polymer polyol (A2) is a polyester polyol.
An adhesive sheet containing a cured product of the adhesive composition according to claim 1 or 2.
A printed wiring board comprising the adhesive sheet according to claim 3 as a constituent element.